1. Field of the Invention
The invention generally relates to an apparatus and method useful for the reattachment of a bone section removed during surgery and, more particularly, to a clamp and cable system for reattaching the dome portion of the greater trochanter to prevent migration of the removed bone section until it fuses to remaining bone.
2. Description of the Related Art
Hip surgery often requires osteotomy of the dome portion of the greater trochanter to access the hip joint. Following such surgery it is important that removed bone portions that are being replaced are secured in place to promote efficient healing through fusion of the replaced portion with the remainder of the femur.
Many surgeons simply reattach the removed trochanter section after implanting a hip prosthesis by wiring the replaced section to the trochanter. This has proved unsatisfactory because of forces that cause the replaced section to shift or rotate when the patient is walking or rising up from a seat. It is not uncommon for surgical wires to break because of the magnitude of these forces.
A trochanter reattachment system used in the past is known as the Dall-Miles system, described in U.S. Pat. No. 4,269,180. This system utilizes an H-shaped clamp which is held in place on the reattached bone section by teeth that engage the outer surface of the domed segment and teeth that are embedded. Cables are passed through holes in the bridge of the clamp and through holes drilled in the femur. The bridge of the clamp is crimped onto the cables to fix them in position.
The Dall-Miles system has experienced cable failure related problems, which are believed to be caused by sharp bends which the cables are forced to make as they exit the bridge of the clamp. Such cable failures not only result in the clamp loosening but also tissue irritation caused by frayed cable ends.
The Dall-Miles system is not particularly effective in providing rotational and vertical stability for the trochanter segment. Since the attachment cables must pass through the single bridge of the H-shaped clamp, the clamp can rotate about the bridge. Vertical stability is also lacking because the clamp is configured such that the cables must pass through the femur only in a single direction in the vicinity of the lesser trochanter.
U.S. patent application Ser. No. 07/994,320 describes a clamp contoured to fit the outer surface of the domed segment of the greater trochanter. The clamp is formed with angled grooves and insertable cable crimping devices for providing improved rotational and vertical stability, while minimizing the possibility of a failure resulting in loosening of the device or the necessity of its removal. U.S. patent application Ser. No. 07/944,320, filed on Dec. 21, 1992, and entitled Bone Section Reattachment Apparatus and Method, is hereby incorporated by reference.
The reliability with which the greater trochanter can be securely reattached to the femur following osteotomy with a device like the one in Ssr. No. 07/994,320 is improved with the substitution of a mechanical element that provides for positive, adjustable clamping across the entire surface that engages the attachment cables. Therefore, there is a perceived need for the use of a clamp wherein a cable is anchored by the controlled movement of a mechanical device.